A brake pressure controller of this kind is known from the European patent description 175 089 B1. For the following reasons, a satisfactory control accuracy cannot be achieved with the prior-art brake pressure controller.
The inlet chamber of the state-of-the-art brake pressure controller is directly connected to the master brake cylinder by a duct so that the hydraulic fluid flows into the inlet chamber without any restriction. As a result, the point at which the proportionally reduced pressure is applied to the rear wheel brakes becomes strongly dependent on the rate of pressure build-up. In this way, in the event of a pressure surge due to a very rapid brake actuation, the proportioned pressure may exceed the desired value as a consequence of the inertia of the regulating piston.
A further disadvantage is that the state-of-the-art brake pressure controller is highly sophisticated and does not offer any reasonable possibility of component pre-assembly. Beyond this, the prior-art brake power controller is not adjustable so that any working tolerance influences the control accuracy.
This has a particular effect on driving safety when the brake power controller is employed as a twin controller in a brake with a diagonal subdivision of the brake circuits, since in that case the tolerances lead to application of different brake pressures in each of the rear wheel brakes.